A gas turbine includes a compressor, a combustor, and a turbine. Air taken in from an air inlet port is turned into high-temperature and high-pressure compressed air, by being compressed by the compressor. In the combustor, fuel is supplied to the compressed air to be combusted. The high-temperature and high-pressure combustion gas drives the turbine, and drives a generator connected to the turbine. In this case, the turbine includes a casing in which a plurality of nozzles and rotor blades are alternately arranged. An output shaft connected to the generator is rotatably driven because the rotor blades are driven by the combustion gas. The combustion gas that drove the turbine is converted into static pressure by a diffuser in an exhaust casing and then released to the atmosphere.
In recent years, higher power and higher efficiency are demanded for the gas turbines formed in this manner, and the temperature of combustion gas guided to the nozzles and rotor blades has been increased. Accordingly, in general, a cooling passage is formed inside the nozzles and rotor blades, and the nozzles and rotor blades are cooled by running coolant medium such as air and steam through the cooling passage. Consequently, while maintaining the heat resistance, the temperature of combustion gas is increased, thereby increasing the power and efficiency of the gas turbine.
For example, in the turbine, an exhaust chamber is connected to the downstream of the exhaust casing in which the nozzles and rotor blades are stored, and an exhaust duct is connected to the downstream of the exhaust chamber. The exhaust casing and the exhaust chamber are connected by a thermal expansion absorbing member in the form of a cylindrical sheet, and the exhaust chamber and the exhaust duct are connected by an expansion joint having an insulator. Accordingly, the thermal stresses between the exhaust casing, the exhaust chamber, and the exhaust duct are absorbed, during heavy load operation and a power increase of the gas turbine.
For example, Patent Documents 1, 2, and 3 below disclose this connection structure of a turbine.
A gas turbine includes a compressor, a combustor, and a turbine. Air taken in from an air inlet port is turned into high-temperature and high-pressure compressed air, by being compressed by the compressor. In the combustor, fuel is supplied to the compressed air to be combusted. The high-temperature and high-pressure combustion gas drives the turbine, and drives a generator connected to the turbine. In this case, the turbine includes a casing in which a plurality of nozzles and rotor blades are alternately arranged. An output shaft connected to the generator is rotatably driven because the rotor blades are driven by the combustion gas. The combustion gas that drove the turbine is converted into static pressure by a diffuser in an exhaust casing and then released to the atmosphere.
In the gas turbine formed in this manner, the exhaust casing in which the nozzles and rotor blades are stored, the exhaust chamber, and the exhaust duct formed in cylindrical shapes are connected, and mounted on the floor in a building by a plurality of legs. The exhaust casing, the exhaust chamber, and the exhaust duct have a double cylindrical shape, because the outer casing and the inner casing are connected by a strut, and a space between the outer casing and the inner casing is a passage for exhaust gas. The legs are connected to both sides of the outer casing, and the exhaust casing, the exhaust chamber, and the exhaust duct are mounted on the floor by the legs.
For example, Patent Document 4 discloses this support structure of a turbine.    [Patent Document 1] Japanese Patent Application Laid-open No. 2006-307733    [Patent Document 2] Japanese Patent Application Laid-open No. 2004-308502    [Patent Document 3] Japanese Utility Model Application Laid-open No. H01-085429    [Patent Document 4] Japanese Patent Application Laid-open No. H07-293277